1. Field of the Invention
The present invention relates to a network system for connecting multiple LANs (Local Area Network).
2. Background Information
Conventionally, network systems have been introduced in various fields as communication technology has developed. For example, in the field of workpiece observation using a charged particle beam created from an electron source or an ion source, or of a charged particle beam apparatus for carrying out microfabrication processing, a system using a network is being proposed.
FIG. 3 is a block diagram of a related focused ion beam apparatus (FIB), a kind of charged particle ion beam apparatus. FIG. 3 shows that a device-side LAN 301 comprising a focused ion beam apparatus with a LAN is installed in a measurement room separately located from the factory and is LAN connected to a factory-side LAN 309 via TCP/IP (Transmission Control Protocol/Internet Protocol).
The device-side LAN 301 is equipped with a host computer 302 for performing input of instructions when carrying out processing such as observing or working of the workpiece, analysis of collected data, or display of workpiece images. In addition, as processing elements, this LAN 301 has an optical system controller 303 for controlling focusing and magnification of an ion beam with an electric field by controlling a condenser lens and a scanning electrode, an optical axis controller 304 for axially aligning an ion source mounted on an ion source stage and positionally aligning a moveable aperture by using an actuator, a vacuum evacuation unit 305 for evacuating the workpiece room where the workpiece is mounted, a workpiece stage 306 for moving the mounted workpiece to the irradiating position of the beam, and a workpiece conveying apparatus 307 for conveying the workpiece to the workpiece stage 306. Further, the host computer 302 is connected to a storage device 310 for storing various data such as image data of the workpiece. Each processing element has a central processing unit (CPU) and is connected to a bus line 308 together with the host computer 302, and these are connected to the CSMA/CD system LANs using TCP/IP. The host computer 302 and each processing element 303˜307 are individually assigned a unique identity (ID) code. The signal exchanged between the host computer 302 and each processing element 303˜307 via the bus line 308 is structured to include the ID code, and the destination of the signal is determined by the ID code of the signal on the bus line 308. In the above structured focused beam apparatus, the host computer 302 and each structural element determine, by using the ID code, whether the signal on the bus line 308 is its own.
When it recognizes its own signal, it responds and processes the signal, and when processing completes, outputs a signal including the ID code of the structural element that will be responsible for the next step on to the bus line 308. Therefore, this system processes observing and working of the workpiece, and data such as image data of the workpiece is stored in the storage device 310.
In the previously mentioned related network system, because the device-side LAN 301 is a part of the factory-side LAN 309, the device-side LAN 301 and the factory-side LAN 309 influence each other causing various problems.
In other words, when the number of accesses from the factory-side LAN 309 to the device-side LAN 301 or apparatuses connected to the factory-side LAN 309 increases, the traffic on the bus line 308 increases and the data transfer efficiency within the device-side LAN 301 slows down. On the other hand, the number of accesses from the device-side LAN 301 to the factory-side LAN 309 increases, and the data transfer efficiency within the device-side LAN 301 also slows down. Further, specifications such as transfer speed and settings such as IP address (Internet Protocol Address) in the device-side LAN 301 are limited by, for example, specifications of the factory-side LAN 309, thus preventing independent specification setting.
Meanwhile, as there is mutually free access between the device-side LAN 301 and the factory-side LAN 309, a third party can intrude into the device-side LAN 301 from the factory-side LAN 309 or vice versa, causing the possibility of confidential information leakage in both the device-side LAN 301 and the factory-side LAN 309.
In addition, as there is a possibility of mutual infiltration between the device-side LAN 301 and the factory-side LAN 309, the device-side LAN 301 cannot be remotely supported by the service center connected with a communication line.
It is also possible to have the same problem when multiple LANs other than the device-side LAN 301 and the factory-side LAN 309 are connected.
The present invention is intended to provide a network system connecting multiple LANs, in which multiple LANs do not influence each other, and the shared data are still accessible from these multiple LANs.
In addition, the present invention also maintains confidentiality while solving the previous problem.
Further, this present invention provides a network system performing maintenance by remote operation as well as solving the previous problems.